Plastic emulsion food spread

ABSTRACT

Margarine and low fat emulsion food spreads have been prepared, the fat phase of which consists essentially of randomized palm oil. The randomization is usually carried out on palm oil alone and enables a substantial amount of palm oil to be incorporated into the fat phase without the onset of excessive post-hardening effects. The randomization also minimizes the amount of expensive vegetable oils such as sunflower oil which have hitherto been found necessary adjuncts with palm oil in such products, particularly in recently-developed soft spreads which can be spread directly at domestic refrigerator temperatures. The major part of the spreads of the invention preferably consist of a fat of melting point 25°-30° C., particularly derived from vegetable oils.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to margarines and like edible emulsion foodspreads of which the fat phase contains palm oil. It is particularlyconcerned with spreads which are soft enough to be spread at domesticrefrigerator temperatures, including those which on account of their lowfat contant are in demand in low calory diets. The more stable of these,like margarine, are of the water-in-oil variety and are similarlyprepared, by chilling, working and resting the previously preparedemulsion, which may contain additional flavouring, colouring, vitaminand emulsifier components similar to those found in conventionalmargarine. These combined operations are nowadays carried out in acontinuous fashion, in scraped surface heat exchangers of the Votatortype and partially crystallise the fat to form a network in which theglobules of the aqueous phase are retained, thus stabilising theemulsion against undesirable accretion of the droplets with consequentemulsion breakdown and multiplication of bacterial growth.

Both the oral response developed upon eating margarine and similar fatspread products and the textural response experienced upon spreadingthem are largely determined by the composition of the fat phase of theproduct. Great skill, much of it of an empirical nature, is needed todevise the most appropriate fat composition, often a blend of many fats,to meet these needs with economic benefit. In recent times an even morestringent requirement needs to be met for so-called soft margarines andsimilar spreads which can be spread directly from storage in domesticrefrigerators, ie about 5° C. This requirement calls for a particularlyflat hardness/temperature response and is a most exacting one to meet.

2. The Prior Art

Palm oil is a cheap and abundant vegetable oil already in widespread usein the Margarine Industry. The limitations imposed upon the amount ofpalm oil that can be included in margarine and like fat spreads relateto its tendency to confer on fat compositions in which it isincorporated, its own slow crystallising characteristics. This leads tothe phenomenon of post-hardening in which a product that is satisfactoryin its textural characteristics when it is initially prepared,subsequently hardens on storage to affect both its oral response when itis said to be grainy, and its ability to spread at ambient or lowertemperatures.

Interesterification as a technique for modifying the characteristics ofpalm oil and to admit of its greater use in the Industry is described in"Margarine" 2nd Edition, Andersen and Williams, 1954 page 3/8-1/3 andthe general description of the technique is given on pages 54 etc. Inthis and in other publications however the palm oil is corandomised witha comparable amount of a second oil, either a lauric oil, vide BritishPat. No. 874,675, a C₁₆ -C₁₈ vegetable oil in a fat formulation thatincludes a substantial trans-acid content combined in the triglyceridesof the fat composition.

In other references, eg Seiden U.S. Pat. No. 3,353,964, similarly acorandomised blend is disclosed, but between lauric fats and fats oflong-chain acids, ie C₂₀ -C₂₂.

Melnick U.S. Pat. No. 2,921,855 describes a corandomised blend, used asa margarine fat, of a triglyceride oil rich in combined polyunsaturatedfatty acid, with a highly hydrogenated fat, while Nelson U.S. Pat. No.2,855,311 discloses the corandomisation of a blend of palm oil with avariety of liquid oils.

In none of these prior disclosures does any suggestion appear that aremedy to overcome the now widely-recognised problem of using palm oilin substantial quantities in emulsion spreads may lie in randomisationessentially of the oil itself, without recourse to the profound changesbrought about in modifying the properties of this oil by distributingits own fatty acid moieties among those of other, distinctly differentfats.

This invention relates to edible fat compositions such as margarines andshortenings in the preparation of which palm oil is used.

Palm oil is readly available and low in cost among vegetable oils and inseveral respects appears suitable for the preparation of edible fatproducts such as margarines and shortenings. Its widespread adoption forthese purposes has however been handicapped in the past by its slow rateof crystallisation, with the result that, long after processing has beencompleted products containing palm oil undergo hardening and sufferother undesirable changes caused by the continued crystallisation of theoil.

It has now been found that margarine products containing substantialquantities of palm oil may be prepared by randomising the palm oil andpreparing a fat blend therewith.

Preferably the palm oil is randomised alone, but it may be corandomisedwith small amounts, not exceeding 10 weight % and preferably less than 5wt %, of other edible oils or fats, whether of vegetable or animalorigin, including marine oil. Similarly, although the palm oil may bemodified somewhat by fractionation or other treatment before beingrandomised, this should essentially impose no major modification uponthe inherent characteristics of the fat.

It is indeed an important feature of the invention that the fatty acidcomposition of the oil remains unchanged, in contrast to the effect ofusing fractionation methods. Similarly, the glyceride composition ofother fats present in the products of the invention remain unchanged, incontrast to corandomisation methods which change the glyceridecomposition of both the palm and the other corandomised fats. Forexample, the glyceride components of palm oil may be separated into ahigh melting stearine fraction and a low melting oleine fraction bysubjecting palm oil to fractional crystallisation, the compositions ofthe fractions differing markedly, to an extent depending upon theconditions of the crystallisation. In accordance with U.S. Pat. No.3,189,465 an oleine fraction obtained in this way is blended with otherfats in margarine formulations. Again, stearine and oleine fractions maybe obtained by subjecting palm oil to directed interesterification,carried out under conditions favouring the continued formation of alimited range of glycerides, usually a stearine fraction separated fromthe liquid phase by carrying out the process at comparatively lowtemperatures. The stearine and oleine fractions obtained in this way,while again differing markedly from one another, are composedessentially of different combinations of the fatty acids of the oil andthus contain different glycerides from those originally present. Thestearine fraction obtained in this way has been proposed for use inshortening compositions.

In both fractionation and directed interesterification methods asubstantial proportion of the palm oil is described. The disadvantagesdescribed may also be overcome, while utilising whole palm oil, bysubjecting it to hydrogenation, but the resultant change in glyceridecomposition that this brings about leads to unsatisfactory meltingcharacteristics in margarine and similar food spreads by producing acloying sensation in the mouth due to the presence of higher meltingglycerides.

A further advantage of the invention is that no other fat need byinvolved in the interesterification. This again provides substantialeconomies and permits the use, in blends with the randomised palm oil,of other fats in proportions providing optimum melting characteristicswhose own melting characteristics are unmodified by corandomisation withthe palm oil. The cool-melting characteristics of lauric fats forexample, which may be present in the products of the invention areaccordingly retained, since they are blended instead of beingcorandomised with palm oil in accordance with earlier proposals.

The invention is particularly useful in the preparation of margarine andlike emulsion fat spreads, which are often required to meet rigidproduct specifications, especially as to their melting and hardnesscharacteristics. In particular, the so-called soft margarines now invogue are required to remain easily spreadable, as table margarines, atdomestic refrigerator temperatures, ie about 5° C., while yet being ofplastic consistency at ambient temperatures, which may be as high as 20°C. These requirements imply a flat response to temperature of hardnessvalue. If this is measured in accordance with the penetration method ofHaighton, then a soft margarine may be described as one having thepenetration range from C₄ less than 900 g/cm² and particularly less than750 g/cm², to C₂₀ between 50 and 150 g/cm² according to the time ofyear. A very small amount of whole or modified palm oil is permissiblein soft spreads, at most about 10 wt % beyond which the product tends tounacceptable hardness.

The invention is particularly suitable for the preparation of fat blendsfor soft margarines, meeting the above requirements for hardness valueswith as much as 40 wt %, in contrast to conventional formulations inwhich not more than 25 wt % is practical in spread formulations, many ofwhich nevertheless fail to meet the above-stated requirements for softspreads, unless a substantial quantity, often as much as 40 wt % or evenmore, of an expensive liquid vegetable oil, for example sunflower oil,is also present. A particular advantage in the invention is that notonly is less oil of this kind necessary, but it may be totally replacedby cheaper oils, for example soybean oil. Preferably the fatcompositions of the invention contain from 15 to 300 wt % palm oil,preferably about 20-25 wt %. The dilatation values of palm oil increasewith randomisation, and amounts in excess of 40 wt % are therefore lessdesirable.

In additon to meeting the above penetration characteristics, the fatcomponent of soft spreads is also required, for good consumer responseto fulfill palatability requirements provided by melting characteristicsthay may be expressed by dilatation values measured in the mannerdescribed in J. Am. Oil Chem. Soc. (1954) 31, pp. 98-103. These shouldlie between about D₅ =600 and D₃₅ below 50. These requirements are metlargely by an appropriate choice of fats or oils with which therandomised palm is blended, and hardness also by adjustment of theconditions under which the fat emulsion is processed. In accordance withcontemporary practice, the spreads of the present invention arepreferably prepared from an emulsion of an aqueous phase in the fatphase, followed by chilling and working the composition to crystallisethe fat, in "Votator" equipment including a scraped surface heatexchange chiller. Other things being equal, greater amounts of palm oilmay be incorporated using longer residence times in the Votator.

In addition to palm oil, the fat blends of the invention may include avariety of other components. A proportion of unrandomised palm oil mayfor example be present, but this should desirably not exceed 10%, sinceit induces post-processing hardening during the shelf-life of thespread, particularly within a few hours of manufacture. Similarly thepresence of unrandomised hardened palm or palm fraction should notexceed 10 wt %.

Other semi-solid fats of the palmitic variety, eg cottonseed oil, may beincluded in similar quantities and lauric fats, eg palm kernel oil,babassu and coconut oils and their fractions, are all suitablecomponents. Several animal fats rich in palmitic acid are also suitable,eg lard and tallow; others include marine oils, for example herring andsardine oils, although these in 10% with general practice may requirehardening treatment by hydrogenation to confer flavour stability. Again,however, preferably not more than 10% and particularly not more than 5%by weight of these fats should be present in the fat composition.

The major part, ie more than 50 wt % of the fat component of the spreadsaccording to the invention is composed of vegetable oils which atambient temperatures, ie 15° C. are liquid, or which are lightlyhydrogenated to a melting point of 15°-30° C. These comprise for examplecorn, groundnut, safflower, sunflower, sesame and soybean oil. Thelatter in particular, being cheap is preferred. In keeping withwidespread practice, it is preferably hydrogenated at least in part tostabilise the oil against deterioration, although the oil may remainlargely unsaturated with an Iodine Value of 90 or more. Besides meetingthe requirement for producing soft, palatable spreads, the choice aswell as the amount of liquid oil is preferably governed by the widelyaccepted desirability of incorporating within the composition glyceridesof the polyunsaturated, so-called essential acids. Preferably the fatcompositions of the invention consist of randomised palm oil and a fator fat blend having a melting point of 25°-30° C. In this specificationthe melting point of a fat means the temperature at which the fatbecomes wholly melted, shown by slowly heating the fat until it turnsclear.

It will be understood that the inveniton may be applied in thepreparation of margarine and of other spreads having a lower fat contentthan is required in margarine. These so-called low fat spreads maycontain as little as 40 wt % fat. The invention is also applicable toshortening compositions in which whole randomised palm oil is blended.

EXAMPLE 1

A margarine fat was prepared by blending various components in thefollowing amounts of weight:

    ______________________________________                                        Soybean Oil   18                                                              Hardened                                                                      Soybean Oil   57 (53% slip m.pt. 28° C. I.V.-105)                                     ( 4% slip m.pt. 36° C. I.V.- 50)                        Interesterified                                                               Palm Oil      21                                                              Hardened                                                                      Palm Oil       4 (Slip m.pt. 45° C. I.V.-45)                           ______________________________________                                    

A margarine emulsion was prepared by agitating the fat at 40° C. in amixture with 16% of an aqueous phase comprising tap water and 0.5 wt %of lecithin and 0.1 wt % based on the fat in the fat phase of a partialglyceride emulsifier and flavouring agents, vitamins, colouring matterand salt in customary amounts.

The water-in-oil emulsion formed was supplied continuously at about 80kg/hr to the first of series of three scraped surface chillers, each 5cm in diameter, 25.5 cms in length and having a chilling surface of 0.04m². Between the first or second pair a pre-crystalliser was interposed,comprising a vessel 3 liters in capacity and also equipped with aclose-fitting agitator but with no chilling capacity. No materialdifference was observed between the two pre-crystallizer positions. Apost-crystalliser of similar construction to the pre-crystalliser buthalf the size, followed the third chiller unit. The equipmentsubstantially reproduced on a smaller scale the effect and operation ofa full-size margarine plant. Residence time in the crystallisers was 3minutes.

The chilled emulsion emerged from the first chiller at about 17.5° C.and gained about 1° C. in the pre-crystalliser, emerging at 16° C. and14° C. from the second and third chiller units and finally at 18°-20° C.from the post-crystalliser, from which it was pour-filled into standard250 gm tubs.

After storage for 3 days at 15° C. and a day at the test temperaturesthe product was tested for hardness. Dilatation values of the fat werealso obtained. The results of the tests are given in Table I.

                  TABLE I                                                         ______________________________________                                                      Hardness                                                        Temp. ° C.                                                                           (C values)   Dilatation                                         ______________________________________                                         5            655 (617)    475                                                10            332 (344)    425                                                15            106 (125)    340                                                20            132 (144)    250                                                35            --            50                                                40            --            10                                                ______________________________________                                    

The product was of pleasing texture at temperatures from 5° to 20° C.,in which range it remained plastic and could be readily spread. Itmelted quickly and readily on the tongue. The melting point of the fatwas 33.3° C.

The experiment was repeated at twice throughput (11/2 minutes' residencetime) while maintaining the same temperature profile and agitator speed.The corresponding characteristics of the product are given in Table I inbrackets.

A series of three comparative trials was carried out based on fatcompositions containing the same ingredients, except for thesubstitution of the randomised palm oil by unrandomised palm oils in theamounts 15, 21 and 25 wt %, the amounts of the remaining ingredientsbeing adjusted as little as possible, to obtain similar dilatationvalues at 5°, 10°, 15°, 20°, 25° and 30° C. These varied less than 10%of the arithmetic mean of the four compositions and at 35° C. the valueswere 35, 35 25 and 55. Nevertheless, the hardened palm and soybean oilcontent remained unchanged and the amount of soybean oil was changedonly comparatively slightly.

The melting points of the comparative fat compositions varied from 31.5°to 33.5° C. None of the margarine products from these trials however,although prepared under the same conditions as before, showed inhardness tests a C₅ value less than 700 and a C₂₀ value within the range50-150, nor could these be obtained by adjustments to the equipment inwhich the emulsions were worked. In only one example was the C₅ valueless than 900 and most were well above 1,000. Similarly, the majority ofthe C₂₀ values were above 150.

EXAMPLE 2

A low fat table spread was prepared from an emulsion consisting of 40 wt% fat phase in which 60 wt % aqueous phase was dispersed, conventionalmargarine additives including colouring matter and emulsifiers beingincluded. The emulsifier was chilled, worked and rested in a series ofVotator A and B units including a precrystalliser unit in which aportion of the processed emulsion containing crystallised fat wasrecirculated to mix with a fresh emulsion.

The fat phase contained by weight the equal parts of refined randomisedpalm oil and soybean oil, and half as much coconut oil. In differentproducts 25% or 50% of the soybean oil was first selectively hardened toa fall of about 25 Iodine Value units to improve flavour stability.

Samples of all the products exhibited satisfactory hardness and dilationcharacteristics, after storage for several weeks at 10° and 20° C., fora soft spread, ie hardness at 5° and 20° C. below 900 and 50-100 anddilatations at 5° and 35° C. about 600 and below 50.

A comparable product with corresponding characteristics was made using afat phase almost 1/3 of which consisted of palm kernel oil and more than40% of sunflower oil. It contained in addition only 10% soybean oil. Notmore than 15% non-randomised palm oil could be included, part of whichwas selectively hardened to give better dilatation characteristics.

What is claimed is:
 1. A plastic emulsion food spread comprising anaqueous phase and a fat phase in the form of an emulsion in which thefat phase is partly crystallized and comprises by weight of the fatphase, from about 5% to about 40% of a triglyceride composition, thefatty acid residues of which are in random distribution and consistessentially of the acid residues of palm oil, and a major proportion ofan additional fat where said fat is selected from the group consistingof corn, cottonseed, groundnut, safflower, sunflower, sesame and soybeanoils.
 2. A food spread according to claim 1 which contains from about 15to about 30 wt % palm oil, based on total fat phase.
 3. A food spreadaccording to claim 1 wherein said spread is in soft tub form, having apenetration range from C₅ less than 900 grams cm² to C₂₀ between 50 and150 grams cm².
 4. A food spread according to claim 1 wherein said spreadcomprises a low fat spread containing by weight of the spread a majorproportion of aqueous phase dispersed in a minor proportion of fatphase.
 5. A method of preparing a water-in-oil emulsion food spreadhaving an enhanced palm oil content, comprising dispersing an aqueousphase in a fat phase to form an emulsion and chilling, working andresting the emulsion to crystallize at least part of the fat phase,wherein the fat phase is prepared by randomizing palm oil and blending,by weight of said fat phase, from about 5 to about 40% of said palm oilwith a major proportion of an additional vegetable oil selected from thegroup consisting of corn, cottonseed, groundnut, safflower, sunflower,sesame and soybean oils.